[Windows] load image with filenames other than english

[dimitre]

The idea behind this PR is to use std::filesystem::path object to store the filename until right up the freeimage function is called. FreeImage has some special functions to handle wstring, so they are called for windows, conserving original encoding.

[dimitre]

Hey @oxillo please check this PR when you have the time. I don't know much about windows but I've tried to fix path encodings there, it seems to be working.

[dimitre]

PS: there is a test there meant to be removed before merge

[dimitre]

I've finally got a windows machine and some time to advance on this PR and test.
I think it is good to merge.
It addresses encoding issues loading files, and with the title in open file dialog box.
I think the only controversial change here is the return type change in of::filesystem::path ofFileDialogResult::getName() and ofFileDialogResult::getPath()

opinions are welcome @ofTheo @oxillo @artificiel @openframeworks/windows

[dimitre]

Hello @ofTheo I think this one is good to go.
Resolves a dread windows problem where you cannot load files in ofSystemLoadDialog with any accentuation and pass correctly to load an ofImage.

There is a test here:
https://github.com/dimitre/ofTests/tree/main/WinEncoding

#7435 (comment)

[dimitre]

@danoli3 can you double check this one if you have the time?
btw, thanks for the other windows PR merging, OF is almost ready to work with multiple languages